U.S. patent number 5,841,494 [Application Number 08/670,451] was granted by the patent office on 1998-11-24 for transflective lcd utilizing chiral liquid crystal filter/mirrors.
Invention is credited to Dennis R. Hall.
United States Patent |
5,841,494 |
Hall |
November 24, 1998 |
Transflective LCD utilizing chiral liquid crystal
filter/mirrors
Abstract
A transflective Liquid Crystal Display (LCD) system is
described, wherein the half silvered mirror is replaced by Chiral
Liquid Crystal (CLC) reflectors/filters, which increase the
reflected and transmitted brightness from over two times to as much
as ten times. These principles are also applied to create an
improved efficiency full color transflective LCD and a number of
high brightness, limited color, displays.
Inventors: |
Hall; Dennis R. (Beaverton,
OR) |
Family
ID: |
24690450 |
Appl.
No.: |
08/670,451 |
Filed: |
June 26, 1996 |
Current U.S.
Class: |
349/98; 349/115;
349/74 |
Current CPC
Class: |
G02F
1/133555 (20130101); G02F 1/133533 (20130101); G02F
1/133536 (20130101); G02F 1/133543 (20210101) |
Current International
Class: |
G02F
1/1335 (20060101); G02F 1/13 (20060101); G02F
001/1347 (); G02F 001/1335 () |
Field of
Search: |
;349/98,74,162,114,115 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Schadt & Funfschilling, 1990 Jpn. J. Appl. Phys., vol. 29, No.
10, pp. 1974-1984, "New Liquid Crystals Polerized Color Projection
Principle". .
Schedt & Funfschilling, 1990, SID 90 Digest, pp. 324-326 "Novel
Polarized Liquid-Crystal Color Projection & New TN-LCD
Operating Modes". .
Maurer, SID 90 Digest, 1990, pp. 110-113, "Polarizing Color Filters
Made From Cholesteric LC-Silicones". .
LiLE & S.M. Faris, SID 96 Applications, 1996, pp. 111-113,
"Single-Layer Super Broadband Reflective Polerizer". .
D. Coates, M. J. Goodlings S. Greenfield, J.M. Hammer, S.A. Marden
& G. L. Parri, SID 96 Applications Digest, 1996, pp.
67-70,"High Performance Wide-Band Reflective Cholesteric
Polarizers"..
|
Primary Examiner: Sikes; William L.
Assistant Examiner: Nguyen; Tiep H.
Claims
I claim:
1. A spatial display means composed of:
A first light polarizing filter, and
an array of polarization modulation cells, and
a multi-element chiral liquid crystal filter/mirror, and
a second light polarizing filter, and
a light source, wherein
ambient room light being polarized by said first light polarizing
filter passes into said array of polarization modulating cells,
said cells having a first switched state that transmits at least
one color of said light in a first polarization state and said
cells having a second switched state that transforms at least said
one color of light to a second polarization state, with
light of said first or second polarization states being imposed
upon said multi-element chiral liquid crystal filter/mirror,
and
said liquid crystal filter/mirror providing transmission of said
light of at least one color, being of said first polarization
state, with
said transmitted light being either absorbed by said second
polarizing filter or passed into said light source, and
said liquid crystal filter/mirror providing reflection of said
light of at least one color, being of said second polarization
state, with
said reflected light transiting said polarization modulation cell
and said first polarizing filter to a viewer, and
said spatial display means having the option to activate said light
source, whereupon,
light from said light source, being of at least one specific color,
is polarized by said second polarizing filter, and
transits said multi-element chiral liquid crystal filter/mirror
into,
said array of polarization modulation cells, said cells having a
first switched state that transmits said light in a first
polarization state and said cells having a second switched state
that transforms said light to a second polarization state, with
said light of said first or second polarization states being
imposed upon said first polarizing filter, whereupon
light of said first polarization state is absorbed by said first
polarizing filter and light of said second polarization state is
transmitted to a viewer.
2. A spatial display means according to claim 1, wherein said first
and second polarizing filters are circularly polarizing filters,
and
said array of polarization modulation cells are specifically an
array of variable retardation cells, with
said cells switching between said first switched state of having
substantially no retardation and intermediate states of
retardation, up to and including said second switched state of
having substantially a half wave of retardation, and
said intermediate states of retardation producing intermediate
intensities or color variations of the light presented to said
viewer.
3. A spatial display means according to claim 1, wherein said
multi-element chiral liquid crystal filter/mirror and said second
light polarizing filter are functionally combined, said combined
element being comprised of at least two chiral liquid crystal
species.
4. A spatial display means according to claim 3, wherein said
combined element is disposed in an array, the specific elements of
said array being incorporated within the cells of said array of
polarization modulation cells.
5. A spatial display means according to claim 1, wherein said
multi-element chiral liquid crystal filter/mirror is disposed in an
array, the specific elements of said array being incorporated
within the cells of said array of polarization modulation
cells.
6. A spatial display means according to claim 5, wherein said
combined element is disposed in at least two sets of combined
elements, within the array of polarization modulation cells,
said sets forming sets of modulation cells, with
the individual sets of said combined elements, reflecting and
transmitting light of substantially uniform color within each set,
but of a color distinct from that respectively reflected and
transmitted by other of said sets, and
having said sets of cells so disposed as to form color picture
elements containing one cell of each of said sets.
7. A spatial display means according to claim 1, wherein said light
source has a spectral distribution excluded by the accumulated
reflective spectral response of said multi-element chiral liquid
crystal filter/mirror.
8. A spatial display means according to claim 1, wherein said array
of polarization modulating cells is disposed between said first
light polarizing filter and said light source, and
said multi-element liquid crystal filter/mirror is disposed between
said array of polarization modulating cells and said light source,
and
said second polarizing filter is disposed between said
multi-element liquid crystal filter/mirror and said light
source.
9. A spatial display means composed of:
A first light polarizing filter, and
an array of polarization modulation cells, and
a quarter wave retardation element, and
a multi-element chiral liquid crystal filter/mirror, and
a second light polarizing filter, and
a light source, wherein
ambient room light being polarized by said first light polarizing
filter passes into said array of polarization modulating cells,
said cells having a first switched state that transmits said light
in a first polarization orientation and said cells having a second
switched state that transforms said light to a second polarization
orientation, with
light of said first and second polarization orientations impinging
upon said quarter wave retardation element, said quarter wave
element transforming said light into polarized light having a
substantial circular polarization component, and whereupon
light of said transformed first or second polarization orientations
comprised light of a first and second polarization states, with
said light being imposed upon said multi-element chiral liquid
crystal filter/mirror, and
said liquid crystal filter/mirror providing transmission of said
light of at least one color, being of said first polarization
state, with
said transmitted light being either absorbed by said second
polarizing filter or passed into said light source, and
said liquid crystal filter/mirror providing reflection of said
light of at least one color, being of said second polarization
state, with
said reflected light of said second polarization state, transiting
said quarter wave element, whereupon said reflected light is
transformed to its original polarization orientation, and
passed through said polarization modulation cell to said first
polarizing filter to a viewer, with
said spatial display means having the option to activate said light
source, whereupon,
light from said light source, being of at least one specific color,
is polarized by said second polarizing filter, and
passes through said multi-element chiral liquid crystal
filter/mirror to said quarter wave element, whereupon
the light is transformed to linearly polarized light, and
the orientation of said transformed linearly polarized light being
controlled by said switched states of said polarization modulation
cells, with
the orientation of said first switched state of said polarization
modulation cells providing an orientation of said linearly
polarized light that is substantially absorbed by said first
polarizing filter, upon which said light impinges, and
the orientation of said second switched state of said polarization
modulation cells providing an orientation of said linearly
polarized light that is substantially transmitted by said first
polarizing filter, upon which said light impinges, and
said transmitted light passing to a viewer.
10. A spatial display means according to claim 9, wherein said
first and second polarizing filters are linearly polarizing
filters, and
said array of polarization modulation cells are specifically an
array of twisted nematic liquid crystal cells, with
said cells switching between said first switched state of having
substantially no rotation of the plane of polarization of the light
transiting said cell and intermediate states, wherein said plane of
linear polarization is rotated up to and including said second
switched state, providing substantially 90.degree. of rotation of
said plane of linear polarization, and wherein
said intermediate states produce intermediate degrees of rotation
providing intermediate intensities or color variations of the light
presented to the viewer.
11. A spatial display means according to claim 9, wherein said
multi-element chiral liquid crystal filter/mirror and said second
light polarizing filter are functionally combined, said combined
element being comprised of at least two chiral liquid crystal
species.
12. A spatial display means according to claim 11, wherein said
multi-element chiral liquid crystal filter/mirror or said combined
element is disposed in an array comprised of at least two sets of
combined elements, with the individual elements of each set being
associated with individual polarization modulation cells,
the individual sets of said combined elements, reflecting and
transmitting light of substantially uniform color within each set,
but of a color distinct from that respectively reflected and
transmitted by other of said sets, and
having said sets of cells so disposed as to form color picture
elements containing one cell of each of said sets.
13. A spatial display means according to claim 9, wherein said
light source has a spectral distribution excluded by the
accumulated reflective spectral response of said multi-element
chiral liquid crystal filter/mirror.
14. A spatial display means according to claim 9, wherein said
array of polarization modulating cells is disposed between said
first light polarizing filter and said light source, and
said multi-element liquid crystal filter/mirror is disposed between
said array of polarization modulating cells and said light source,
and
said second polarizing filter is disposed between said
multi-element liquid crystal filter/mirror and said light source,
and
said quarter wave retardation element is disposed between said
array of polarization modulation cells and said multi-element
liquid crystal filter/mirror.
15. A spatial display means composed of:
a first light polarizing filter, and
an array of polarization modulation cells, and
an array of multi-element chiral liquid crystal filter/mirror
elements, disposed in at least two sets of color encoding elements,
each set reflecting and transmitting light of substantially uniform
color in at least one of two switched states of said polarization
modulating cells and each element of each set being associated with
individual cells of said array of polarization modulation cells,
said sets of cells so disposed as to form color picture elements
containing one cell of each of said sets, and
a second light polarizing filter, and
a light source, wherein
light from said light source is polarized to a first state by said
second light polarizing filter, with
said light passing into said array of polarization modulation
cells, said cells having a first switched state that transmits said
light in a first polarization state and said cells having a second
switched state that transforms said light to a second polarization
state, with
said light of a said first and second polarization states being
imposed upon said array of multi-element chiral liquid crystal
filter/mirror elements, and
said light of said first polarization state in a first embodiment
being reflected by said liquid crystal filter/mirror elements,
returning said light to the light source where it is absorbed or in
a second embodiment, having said light of said first polarization
state being transmitted by said liquid crystal filter/mirror
elements to said first light polarizing filter, where it is
absorbed, and
having in said first and second embodiments, at least one color of
said light of said second polarization state being reflected by
said liquid crystal filter/mirror elements and returned to said
light source, with the remainder of said light passing to a viewer,
with
said light passing through said first light polarizing filter to a
viewer in said second embodiment.
16. A spatial display means according to claim 15, wherein said
array of multi-element chiral liquid crystal filter/mirror elements
is disposed between said optional first light polarizing filter and
said light source, and
said array of polarization modulation cells being disposed between
said array of multi-element chiral liquid crystal filter/mirror
elements and said light source, with
said second light polarizing filter being disposed between said
array of polarization modulation cells and said light source.
17. A spatial display means according to claim 15, wherein said
optional first and second light polarizing filters are circularly
polarizing filters, and
said array of polarization modulation cells are specifically an
array of variable retardation cells, with
said first switched state producing substantially no retardation
and said second switched states constituting a half wave of
retardation, and
having intermediate switched states that produce intermediate
degrees of retardation, and
said intermediate degrees of retardation producing intermediate
intensities or color variations of the light presented to said
viewer.
18. A spatial display means according to claim 15, wherein said
array of multi-element liquid crystal filter/mirror elements are in
at least two sets of color elements, within the array of
polarization modulation cells,
said sets of color elements forming sets of modulation cells,
with
the individual sets of said color elements transmitting light of
substantially uniform color and polarization within each set for a
given switched state of said modulation cells, said color being
distinct from the color of the light transmitted by color elements
of other said sets, and
having said sets of cells so disposed as to form color picture
elements containing one cell of each of said color element
sets.
19. A spatial display means according to claim 15, wherein said
light passing to a viewer is first projected upon a display screen,
wherein said light reflected or transmitted to said viewer.
20. A spatial display means according to claim 15, wherein said
viewer directly views said spatial display.
21. A spatial display means according to claim 15, wherein said
array of multi-element chiral liquid crystal filter/mirror elements
and said first light polarizing filter are functionally combined,
said combined element being comprised of at least two chiral liquid
crystal species.
Description
BACKGROUND OF THE INVENTION
1. Statement of the Invention
This invention relates to Liquid Crystal Display (LCD) devices and
in particular to LCDs of the transflective type. Transflective LCDs
are a dual mode display device. These devices operate either with
the available ambient light in a reflective mode or with an
internal light source in the transmissive mode. The devices of this
invention use cholesteric liquid crystal filter/mirrors, to
reflect, filter and direct polarized light within the devices. The
embodiments of the invention provide improvements of brightness or
battery life. This application is related to Disclosure Document
357140 filed in the Patent and Trademark Office on Jul. 15, 1994.
The contents of Disclosure Document 357140 are hereby incorporated
by reference herein. Many of the embodiments of this application
were recorded in the Engineering Notebook of Dennis R. Hall on Sep.
22, 1992, this reference is also incorporated herein.
2. Description of the Prior Art
The methods of transmissive and reflective LCDs are well known, but
the methods of the transflective LCD, being a combination of these
methods is less well understood. FIG. 1 illustrates the components
of the present day transflective LCD system. In the reflective
mode, the room light 1 passes through the outside polarizer 2,
which linearly polarizes the light 2a which then passes through the
front electrodes 3 into the LCD cell 4. While cells having positive
dielectric anisotropy are possible, for the sake of simplicity, it
will be assumed that the cell 4 has the more popular negative
dielectric anisotropy. Thus, when a cell of the LCD is in the "on"
state, the cell has no effect upon the light passing through it.
When the cell is "off", the light passing though the cell will be
altered in some way, depending upon the nature of the light and the
type of LCD. In the illustration of FIG. 1, the LCD cell 4
functions in what is known as the "wave guide mode" to rotate the
plane of polarization of the light 2a and 7a passing through it 4
in the "off" state. The light 2a passing through the LCD cell 4
encounters the rear electrodes 5 and passes through the backplate
6, exiting the LCD. External to the LCD in this illustration is the
inside polarizer 7. This 7 is also a linear polarizer, which is
usually oriented orthogonally to the outside polarizer 2. If the
LCD cell 4 is "on" the ambient light 2a passing to the inside
polarizer 7, is absorbed. When the LCD cell 4 is "off", the light
proceeds through the inside polarizer 7 to the half-silvered mirror
8. At the mirror 8, about 26 to 39% of this light 2a is reflected,
having its polarization preserved. The reflected light then returns
through the inside polarizer 7, through the LCD cell 4 ("off"
state) and finally through the outside polarizer 2 to the viewer 9.
Assuming excellent anti-reflection (AR) coatings on all surfaces
and high efficiency polarizers (44%), only 8 to 12% of the ambient
light that falls on the display is returned to the viewer 9. In
most applications polarizers of somewhat lesser efficiency (38%)
are used in order to have improved contrast, since the higher
efficiency polarizers do not adequately polarize light of the
entire visible spectrum.
In the transmissive mode, some of the light 10 from the light
source 11, which is usually a Light Emitting Diode (LED), an
Electroluminescent (EL) panel or a cold cathode fluorescent tube,
passes through the half-silvered mirror 8 to the inside polarizer
7, the backplate 6 and into the LCD cell 4. When a cell 4 is "on"
the Linearly Polarized Light (LPL) 7a passes unaltered to the
outside polarizer 2 where it is absorbed. In the case where the
cell 4 is "off", the plane of polarization is rotated and the light
7a passes through the outside polarizer 2 and to the viewer 9. In
this case only about 10 to 25% of the light passes the
half-silvered mirror 8 and all but 44% of this is absorbed by the
inside polarizer 7. Finally the outside polarizer 2 passes nearly
90% of the aligned polarized light 7a. Thus, between 4 and 10% of
the light is passed to the viewer 9 in the transmissive mode.
The low efficiency of the prior art is vastly improved by the
methods of the invention. The efficiency is important because the
size, weight and battery life of portable instrumentation are
heavily dependent upon the efficiency of the instrumentation's
display. The invention uses filter/mirrors comprised of Cholesteric
type liquid crystal material. This material can more generally be
called Chiral Liquid Crystals (CLC). Material having different
color or polarization characteristics (specie) can be intermixed
when each specific specie of the material is disposed in
micro-capsules. However, most often the material is disposed in
specie specific layers, with the layers superimposed coextensively
to create the desired filter/mirror. The reflection characteristics
of the CLC layers are illustrated in FIG. 3 and discussed in some
detail by Schadt & Funfschilling cf. Schadt &
Funfschilling, 1990 Jpn. J. Appl. Phys., vol. 29, No. 10, pp 1974
-1984, New Liquid Crystal Polarized Color Projection Principle and
Schadt & Funfschilling, SID 90 Digest, 1990, pp 324-326, Novel
Polarized Liquid-Crystal Color Projection and New TN-LCD Operating
Modes. When, properly aligned and deposited CLC layers are exposed
to broad spectrum unpolarized light, the light of each CLC layer's
spectral range is broken into equal amounts of Right Hand (RH) and
Left Hand (LH) Circularly Polarized Light (CPL). Virtually all the
light of one handedness is reflected over the spectral range. When
the CLC layers are exposed to CPL, virtually all the CPL will be
transmitted or reflected, depending upon the handedness and color
of the light and specie(s) of the CLC. However, the reflected CPL
does not experience a handedness change upon reflection from the
CLC, as it would from a specular reflector (common mirror). Each
specie of the CLC material has a color or center wavelength which
is determined by the pitch length of the LC structure. This pitch
can be adjusted by the amount of chiraling agent used in the
synthesis of the CLC or by polymerizing the CLC at the temperature
at which the CLC reflects the desired color, cf. Maurer, SID 90
Digest, 1990, pp 110-113, Polarizing Color Filters Made From
Cholesteric LC-Silicones. The frequency or wavelength distribution
(bandwidth) of the reflected light is a function of the
birefringence of the CLC, which can be adjusted by the selection of
the liquid crystal used. Any number of layers of the CLC can be
superimposed to create the desired filter/mirror, including layers
of both handednesses.
SUMMARY OF THE INVENTION
The first embodiment of the invention is illustrated in FIG. 2.
This illustration is somewhat cumbersome, but because of its
similarity in form and function to the prior art, it will serve to
simply illustrate the similarities and differences between the
invention and the prior art.
A LED light source 11 has been selected for the illustration in
both cases, but in either cased a variety of other light sources
could be used. The only stipulation being that the light source for
the new art should be of a narrow emission band.
In FIG. 2, the ambient room light 1 enters the LCD 4 through the
outside polarizer 12, which is a right hand circular polarizer,
sending Right Hand Circularly Polarized Light (RHCPL) 12a into the
cells 4 of the LCD. The cells 4 that are "on", pass the light 12a
through the LCD 4 unaltered as in the case of the prior art. But
the LCD 4 of this embodiment is fashioned such that an "off" cell
forms a birefringent half wave element, which converts the RHCPL to
Left Hand Circularly Polarized Light (LHCPL). The light 12a then
passes through the exit electrodes 5, the backplate 6 and
encounters a two layer filter/mirror 13. The filter/mirror 13 is
comprised of two CLC layers 14 and 15, the characteristics of which
are illustrated in FIG. 3.
In this embodiment, a red LED backlight 11 was selected and the two
layer filter/mirror 13 was made to transmit the red light 17a,
derived from the polarization of the light 10 from the backlight 11
in FIG. 2. The two layer filter/mirror 13, as illustrated, will
reflect about 48% of all incident light over about 90% of the human
eye response corrected spectrum, leaving a notch or transmissive
area in the red. The transmissive area corresponds to the spectral
distribution of the red LED light 10, which is shown as the
spectral distribution 16 in FIG. 3.
In FIG. 2, the switching logic of the prior art case is retained
and the two layer filter/mirror 13 is made to reflect LHCPL in the
blue and green region. Thus, when the LCD cells are "on" and the
Right Hand Circularly Polarized (RHCP) ambient light 12a enters the
cell 4, the light 12a is unaltered and travels through the exit
electrodes 5, the backplate 6 and the two layer filter/mirror 13 to
the inside polarizer 17. This 17 is a Left Hand (LH) circularly
polarizing filter that absorbs the RHCP ambient light. However,
then the cell 4 is "off", the light 12a passing through the LCD 4
cell, has its handedness changed. Thus light 12a becomes LH
circularly polarized and when encountering the two layer
filter/mirror 13, the blue and green colors of the light 12a are
reflected, retaining its LH circular polarization. The reflected
light passes back through the backplate 6 and exit electrodes 5,
into the LCD cell 4. The cell 4 being "off", changes the handedness
of the light, returning it to RHCPL, which can pass through the
outside polarizer 12 to the viewer 9. The red ambient light 12a
passed through the two layer filter/mirror 13 and inside polarizer
17, into the light source 11 region where it is absorbed or
returned through the cell 4 to the viewer. Using the same
efficiency criterion as in the prior art case, one finds that about
33.5% of the ambient light is returned to the viewer, as compared
to the 8 to 12% in the earlier case, for about a three times
improvement.
In the transmissive case the improvement is even greater, since the
two layer filter/mirror 13 has no effect upon the transmitted
circularly polarized red light 17a. Thus, the method of operation
and the efficiency is the same as a conventional "transmissive
only" LCD or about 39%, compared to the 4 to 10% figures found for
the transflective device in this mode. This yields an average
improvement of about seven times. However, one should note that
these comparisons may not be directly equivalent, since the
spectral distribution of the reflected and transmitted light are
not spectrally the same. The device of the prior art can reflect or
transmit light across the entire spectrum, whereas the invention
excludes from reflection, the spectral region transmitted by the
device. Thus, depending upon which spectral region is transmitted,
the reflective efficiency can be impacted to a greater or lesser
extent. On the other hand, the new art does present an advantage
relative to the transmissive only LCD in that, in the transmissive
mode the brightness of the cell is further increased by the light
reflected by the cell. As long as there is some ambient light, the
devices of this invention will be brighter than the "transmissive
only" LCD device. Aside from an AR coating on the outside polarizer
12, no AR coatings are required, because the outside polarizer will
absorb the undesired reflected light. Although some AR coatings may
be desirable to enhance the efficiency.
In the illustrations of FIGS. 1 and 2, the polarizers and
reflectors are shown external to the LCD. In this case a very thin
backplate 6 must be used to minimize parallax induced viewing
problems. However, the CLC filter/mirrors of the present invention
are compatible with the nematic LCs of the LCD. They can also be
made very thin ( as thin as one micron per layer), so that they
could be incorporated within the LCD cell (deposited upon the
cell's electrodes) without severely impacting the switching
sensitivity of the cells. This then eliminates the parallax
problems and greatly enhances the viewing angle of these devices,
in the reflective viewing mode. Most of the devices of the
preferred embodiments, will be illustrated with the CLC
filter/mirrors incorporated within the LCD cells.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of the prior art in transflective LCD
devices.
FIG. 2 is an illustration of a cumbersome embodiment of the
invention.
FIG. 3 is a graphic representation of the spectral distributions of
the light reflected from LC filter/mirror layers and that of the
light source of a LCD.
FIG. 4 is an illustration of a simplified embodiment of the
invention.
FIG. 5 is an illustration of the invention in which the LCD
functions in the wave guide mode.
FIG. 6 is an illustration of the invention as it may be applied for
a full color LCD.
FIG. 7 is an illustration of the invention as it may be applied for
a full color LCD operating in the "wave guide" mode.
FIGS. 8 illustrates the reflective spectral distribution curves for
a family of the CLC color filter/mirrors.
FIGS. 9 illustrate the transmission spectral distribution curves
for a family of the CLC color filter/mirrors.
FIG. 10 illustrates the white light spectral distribution and
intensity from using the complementary (broad band) color
filter/mirror system.
FIG. 11 illustrates the white light distribution from using the
narrow band color filter/mirror system.
FIG. 12 illustrates the half tone characteristics of using the LCD
cell in the birefringence mode.
FIG. 13A illustrates a high brightness color transflective
device.
FIG. 13B illustrates a variation of the embodiment of FIG. 13A
optimized for reflective mode viewing.
FIG. 14 illustrates the triad details for the embodiments of FIGS.
13.
FIG. 15 illustrates the spectral distribution of a high brightness
triad producing a complementary color.
FIG. 16 illustrates the spectral distribution of a high brightness
triad producing a primary color.
FIG. 17 illustrates the spectral distribution of a high brightness
triad producing a primary color in a further embodiment of the
invention.
FIG. 18 illustrates the embodiment of a novel transmissive LCD.
FIG. 19 illustrates the above embodiment in a projection
application.
FIG. 20A illustrates the triad details of the embodiments of FIGS.
18 and 19, configured to produce high brightness, complementary
color display.
FIG. 20B illustrates the triad details of the embodiments of FIGS.
18 and 19, configured to produce a primary color display.
FIG. 21 illustrates a configuration that reduces the number of CLC
filter layer required in certain embodiments illustrated in FIGS.
18 and 19.
PREFERRED EMBODIMENTS OF THE INVENTION
One way to eliminate the inside polarizer 17 of the initial
embodiment, is illustrated in FIG. 4. The two layer filter/mirror
13 is changed to a three layer filter/mirror 18, comprising the two
previously described layers and an additional layer to polarize the
backlight 10. The three layer filter/mirror 18 is comprised of CLC
layers which reflect LHCP blue and green light and a layer that
reflect RHCP red (light source) light. The last layer then
transmits the LHCPL of the light source 11 through the three layer
filter/mirror 18, while reflecting the RHCPL of the source light
10, back to the source 11. The light source area 11 should be
generally light absorbing, to minimize the ambient light 1 that
passes through the three layer filter/mirror 18 into the light
source region 11, from being reflected and passing back through the
three layer filter/mirror 18 to degrade the contrast of the
display. This may be minimized by retaining the design of FIG. 2,
but placing the two layer filter/mirror 13 within the LCD cells 4
as illustrated with the placement of three layer filter/mirrors 18
in FIG. 4. As broader band CLC materials become available, the two
layer filter/mirror can obviously be constructed as a single layer
filter/mirror and the three layer filter/mirror can be made as a
two layer filter/mirror. Work on such broad band materials are
evidenced by the papers of D. Coates et al, D. Coates, M. J.
Goulding, S. Greenfield, J. M. Hammer, S. A. Marden and G. L.
Parri, SID 96 Applications Digest, 1996, pp 67-70, High Performance
Wide-Band Reflective Cholesteric Polarizers and Li et al, L. Li and
S. M. Faris, SID 96 Applications Digest, 1996, pp 111-113,
Single-Layer Super Broadband Reflective Polarizer.
In the reflective mode, the ambient light 1 impinges on the outside
polarizer 12, which transmits RHCPL 12a into the cell 4. When the
cell 4 is "on" the light 12a is unaltered and passes to the three
layer filter/mirror 18, which passes the light 12a into the
absorptive light source 11. When the cell 4 is in the "off" state,
the light 12a entering the cell 4 is converted to LHCPL and the
blue and green colors of the light 12a are reflected by the three
layer filter/mirror 18. The red LHCPL 12a proceeds through the
filter/mirror 18 and is absorbed in the light source 11.
In the transmissive mode the light 10 from the light source 11 is
circularly polarized by the three layer filter/mirror 18. This
LHCPL 18a is of a single color (red in this example). When the cell
4 is "on" the light 18a is unaltered by the cell 4 and passes to
the outside polarizer. Since the outside polarizer 12 transmits
only RHCPL, the light 18a is absorbed and the viewer sees a black
pixel. However, when the cell 4 is in the "off" state, the light
18a entering the cell 4 is converted to RHCPL, which is transmitted
by the outside polarizer 12, to the viewer 9.
The principal embodiments of this invention uses birefringent LCD
cells 4, which have certain advantages, cf. Schadt &
Funfschilling references. However, many of the present day
commercial LCDs operate in the wave guide mode. In this mode the
LCDs have less spectral sensitivity and greater tolerance on the
thickness of the LCD cells. Thus, a version of this invention that
operates in the wave guide mode is presented in FIG. 5. This
embodiment is illustrated with the CLC filter/mirrors located
external to the LCD, since methods are not available to fabricate a
suitable quarter wave element 19, within the LCD cell 4.
In the reflective mode, the ambient room light 1 is linearly
polarized by the outside polarizer 2 before entering the LCD cell
4. When the cell 4 is "on", the light 2a passes unaltered through
the cell 4, the exit electrodes and the backplate 6. The LPL 2a
then encounters the quarter waveplate 19 such that its 19 optical
axes are oriented at an angle of 45.degree. to the plane of
polarization of the LPL. The quarter waveplate converts the LPL to
RHCPL. This light then encounters the three layer filter/mirror 18,
which passes the light into the absorptive light source area 11.
However, when the cell is in its "off" state, the plane of
polarization is rotated 90.degree. by the LCD cell 4. This places
the plane of polarization at an angle of -45.degree. to the optical
axis of the quarter waveplate 19, changing the polarization of the
light 2a to LHCPL. This light 2a then encounters the three layer
filter/mirror 18, using the same species of CLC described earlier,
the filter/mirror 18 reflects the LHCP green and blue light back to
the quarter waveplate 19. The red light 2a is transmitted into the
light source 11, where it is absorbed. The reflected LHCPL enters
the quarter waveplate 19 and becomes linearly polarized light 19a,
with its plane of polarization oriented orthogonally to the plane
of transmission of the outside polarizer 2. When this light 19a
passes through the "off" LCD cell 4, the plane of polarization is
rotated and becomes aligned to the transmitted axis of the outside
polarizer 2, so that it 19a can pass to the viewer 9. In the
transmissive mode the light 10 from the light source 11 is
circularly polarized by the three layer filter/mirror 18. This
LHCPL is of a single color (red in this example), which is then
converted to LPL 19a by the quarter waveplate 19. When the LCD cell
4 is "on" the LPL 19a from the light source 11 is blocked by the
outside polarizer 2, but when the cell is "off" the LCD cell 4
rotates the plane of polarization of the light 19a through
90.degree.. This then aligns the plane of polarization of the light
19a to that orientation that is transmitted by the outside
polarizer 2 and the light 19a passes to the viewer 9.
With properly bonded filters the efficiency of this system is
better than either the conventional reflective or transmissive
LCDs. This is because the CLC filter/mirror 18 used as either a
polarizer or as a reflector, is more efficient than even the best
absorptive polarizers. The table below illustrates, how the devices
thus far described, compare to the state of the art LCDs.
______________________________________ Device Device Device
Conventional Conventional of of of Transflective Single Mode FIG. 2
FIG. 4 FIG. 5 ______________________________________ Transmissive
4-10% 39% 39% 42% 40% Reflective 8-12% 28.5% 33.5%* 33.5%* 30.5%*
______________________________________ *These figures are valid for
a red backlight and the use of most other color backlights will
diminish these figures.
Note that these devices, including the conventional transflective
device, can operate in both modes at the same time. Thus, the
apparent brightness can be more than double that of the fixed mode
devices.
The Maurer reference describes a special CLC formulation which can
be applied in thin layers by a number of means and then made solid
by cross-linking the molecules, whereupon other thin layers can be
applied and made solid, until one has the desired filter/mirror.
This process enables one to fabricate extremely thin
filter/mirrors, which are essential for designs incorporating the
CLC filter/mirrors within the LCD cells. This material is marketed
by Wacker Chemie.
Another preferred embodiment is that of the full color
transflective LCD. This is largely any of the above devices in
which the CLC color filter/mirrors can be placed in the individual
cells, so that triads of color elements are created. Two of these
embodiments are illustrated in FIGS. 6 and 7.
The device of FIG. 6 operates in a birefringence mode, where the
color cells switch from a state of having no effect upon the light
12a and 17a passing through them ("on" state) to becoming a half
wave element ("off" state). A halfwave element changes one
handedness of CPL to the other, orthogonal handedness. In the
embodiment of FIG. 6, some of the ambient room light 1 passes
through the outside polarizer 12 becoming RHCPL 12a, which passes
unaltered through an "on" cell 4. This light 12a proceeds to the
CLC color elements 20, which reflect LHCPL. The light 12a continues
to the inside polarizer 17 where it is absorbed. When the cell 4 is
in the "off" state, the light 12a passing through it 4 has it
handedness changed to LHCPL wherein one color of which is reflected
by the color element 20. The unreflected light 12a proceeds to the
inside polarizer 17, which transmits the light 12a into the light
source 11, where it is absorbed or reflected. In the transmissive
mode, light 10 from the light source 11 is polarized to LHCPL by
the inside polarizer 17. This light 17a passes through the
backplate 6 and rear electrodes 5 to the CLC color elements 20,
which reflect one color of the LHCPL 17a back through the inside
polarizer 17 into the light source 11. The light 17a that was not
reflected by the color element 20 is of the complementary color to
that which was reflected. This light 17a enters the LCD cell 4. If
the cell 4 "on", the light 17a is unaffected and is absorbed by the
outside polarizer. When the cell 4 is "off", the handedness of the
LHCPL 17a is changed to RHCPL and the light 17a is transmitted by
the outside polarizer 12, to the viewer 9.
The device of FIG. 7 operates in the wave guide mode, where the
outside polarizer 2 is a linear polarizer and the plane of
polarization is rotated when the LCD cells 4 are switched. But,
since the CLC color elements 20 reflect CPL, the LPL must be
changed to CPL by a quarter waveplate 19. The waveplate 19 and the
color elements 20 are shown external to the LCD cell 4. Depending
upon the orientation of the LPL 2a to the optical axis
(.+-.45.degree.) of the waveplate 19, either RHCPL or LHCPL reaches
the CLC color elements 20. As noted, the LCD cell 4 controls the
orientation of the LPL 2a relative to the waveplate 19. With the
transformation of LPL to CPL and CPL to LPL, being made by the
quarter waveplate 19, this device operates the same as the device
of FIG. 6, in both the reflective and transmissive modes.
Like the monochrome transflective devices of the invention, the
color embodiments of the invention yield displays of complimentary
color in the reflective and transmissive modes. Thus when there is
sufficient ambient light and the backlight is turned "on", a black
and white display may result. The embodiment of FIGS. 6 and 7,
produce light described as being of a complementary color between
the transmissive and reflective modes. As so configured, the light
from the individual LCD cells is comprised of two of the three
colors. This arrangement has a twofold effect. First, the
saturation of the colors in the transmissive mode are considerably
reduced, resulting in a reduced color gamut. Secondly, brightness
of the transmissive display can be greatly increased, by
re-configuring the video color signals. This then allows the use of
less backlight and improved battery life in portable units.
FIGS. 8 illustrate the reflective spectral distribution of a family
of CLC filter/mirrors, when exposed to unpolarized white light. The
individual curves illustrate the basic characteristic of the CLC
filter/mirrors. FIG. 8A illustrates the red reflecting CLC, whereas
FIGS. 8B and 8C illustrate the characteristics of the green and
blue reflecting material, respectively.
FIGS. 9 illustrate the transmission characteristics of the
individual color cells or sub-pixels for a white backlight 11,
having a handedness that is reflected by the CLC color element 20
of FIGS. 6 or 7. The transmitted colors are those colors that are
not reflected by the specific color element(s) 20 of the individual
LCD cell 4. When viewed or measured at the pixel level (comprised
of the three color sub-pixels), the white brightness is doubled, as
illustrated in FIG. 10. FIG. 10 also shows the individual
distributions of FIG. 9, consolidated on one graph, illustrating
how the individual distributions combine to double the brightness
of the transmissive display. The doubling of brightness results
from having each sub-pixel transmitting light of two primary
colors. In this case a sub-pixel only removes the light of one
color from the illuminating light 10, rather than the usual light
of two colors. However, the method results in a greatly reduced
color gamut. Yet, for the situation where the brightness of battery
operated LCD's is marginal or the battery life must be lengthened,
this compromise is reasonable. In this instance, the complementary
color format is used only in the transmissive mode, where power
consumption by the display backlight is high.
FIG. 11 illustrates a reflective white light spectral distribution
25, comprised of the individual spectral distributions of the color
elements 20 within a three color element pixel of the display.
These displays can generate halftone or intermediate color states.
FIG. 12 illustrates the switching of the LCD cell 4 from "on" to
1/8 wave beyond "off". The 1/8 wave beyond the "off" state is
achieved by making the cell 4 that has sufficient retardation to
produce an additional 1/8 wave retardation beyond that which is
generally required. In the operation of a cell 4, such as
illustrated in FIG. 6, the "off" state is a slightly biased state,
that is nevertheless referred to as the "off state". RHCPL 12a from
the outside polarizer 12 is passed through a LCD cell 4 to a CLC
color element 20. When the cell 4 is "on" the light passes through
the cell 4 unaltered (no retardation) and the light passes through
the CLC color element 20 into the inside polarizer 17 or the light
source 11. When the cell 4 produces a 1/2 wave of retardation, the
light 12a of specific colors, is reflected by the CLC color element
20. FIG. 12 illustrates that between the fully switched states, the
amount of light reflected from the color elements 20, varies as the
sin.sup.2 of half the retardation angle, e.g. 90.degree. for a 1/2
wave (180.degree.) of retardation. FIG. 12 also shows the
configuration of the light 12a at the CLC color element(s) 20.
Elliptically Polarized Light (EPL) of either handedness can be
modeled as a combination of LPL and CPL. The light is modulated by
virtue of the fact that all the LHCPL and half of the LPL is
reflected by the color element 20 as LHCPL and all the light
transmitted by the color element 20 is RHCPL. Thus, as the
retardation of the cell 4 is increased and the amount of right hand
and/or linear components of the light is reduced, more LHCPL is
reflected by the color element 20, as illustrated.
It might also be noted that the cell 4 can be easily adjusted to
compensate for chromatic path length differences between the sets
of color cells by varying the thickness of the CLC color elements
20. This is possible since thickness variation in the required
range has no effect upon the color elements 20 characteristics.
Thus, cells or each color can be made that are very nearly perfect
half wave retarders, having the same bias voltage applied to the
cells of a pixel.
Another embodiment of the invention is a transflective device
offering its best performance in the reflective mode. This
embodiment is very similar to the device of FIG. 6 and it can be
configured that way or in a number of other ways (four ways for
each combination of triad filter/mirrors). For illustration, the
configuration of FIG. 13A was chosen. The unique aspect of this
embodiment is that the triad color elements are comprised of three
layer filter/mirrors, as illustrated in FIG. 14. These
filter/mirror layers are superimposed, as are the two layer
filter/mirrors of FIGS. 2 & 4 and the three layer
filter/mirrors of FIGS. 5 & 6, but the extent of these
filter/mirrors, as illustrated in FIG. 13A is limited to the
individual color elements. The most unique aspect of this
embodiment is that in the reflective mode, all of the sub-pixels
are always reflecting light. In addition, the sub-pixels can
reflect light of two colors, so the effect is up to a five fold
increase in the reflected light flux, but with reduced brightness
contrast.
The operation of this embodiment is much like the previous
examples. The room light 1 is right hand circularly polarized by
the outside polarizer 12 and when a cell 4 is "on" the light 12a is
unaltered as it passes through the cell 4. When the light 12a
reaches the color elements 26, sub-pixel "X" reflects red,
sub-pixel "Y" reflects green and sub-pixel "Z" reflects blue. The
colors of light 12a not reflected in each sub-pixel are transmitted
to the inside polarizer 17 where they are absorbed. When a LCD cell
4 is "off" the light 12a is changed to LHCPL and sub-pixel "X"
reflect both the green and blue components of the light 12a
impinging upon it. Sub-pixel "Y" reflect the red and blue
components of the light 12a and the sub-pixel "Z" reflect the red
and green components of the light 12a. When the reflected light
traverses back through the "off" cell, this light is again
converted to RHCPL, which is transmitted by the outside polarizer
12 to the viewer 9. The component colors of light 12a not reflected
at the individual sub-pixels, pass through the inside polarizer 17
to the light source 11, where it is absorbed. Since the three
sub-pixels can be switched to two levels, there are eight fully
switched states each triad can produce. This is illustrated in
Table I, by designations of states "A" through "H". The spectral
distributions from a pixel can be configured in four basic ways.
First is a background, or low level "white state" distribution,
where each sub-pixel produces only one color, yielding a spectral
distribution 25 as illustrated in FIG. 11. Secondly, is a
configuration wherein the light from the pixel is comprised of two
colors as illustrated in FIG. 15. In this configuration the colors
are produced in combination (two colors) within one sub-pixel with
each of the other sub-pixels producing one of the two colors. The
third configuration involves creating colors derived from all three
colors as illustrated in FIG. 16. In this configuration the colors
are produced in combination within two sub-pixel with the other
sub-pixel producing one of the three colors, that color being the
principal color of the distribution. Note that the spectral
distribution of this three color configuration includes the entire
spectrum, with a significant spectral peak in one color, that color
being the color principally perceived by the viewer. The flux from
the skirts of the distribution serve to enhance viewability of that
color, although the color is considerably less saturated, than if
the skirts of distribution were not present. The emphasis is upon
viewability, not color purity. The fourth configuration is a "super
white" state, wherein each sub-pixel produces two colors. The
distribution is essentially the same as illustrated in FIG. 11, but
the brightness is twice as great as the earlier configuration. A
display having a two to one or less brightness contrast may be
considered inadequate by some people, until they consider other
factors. These factors are the viewability of color contrast
displays at monotonic brightness levels and the intended
applications for such displays. These applications are for low
power consuming color displays in low ambient light
environments.
In the transmissive mode of the device of FIG. 13A, the backlight
is polarized to LHCPL by the inside polarizer 17. Thus, the light
going through the sub-pixel "X" is LHCP red light, the light at
sub-pixel "Y" is LHCP green light and light at sub-pixel "Z" is
LHCP blue light. Then, if the LCD cell 4 is "on", this light 17a is
unaffected by the cell 4 and travels to the outside polarizer 12,
where it is absorbed, providing a "black" state. When the cell 4 is
"off" the LHCPL is changed to RHCPL and is transmitted through the
outside polarizer 12 to the viewer 9. Table I shows the color of
the light relative to the switched state of the display. This
embodiment behaves as a conventional transmissive LCD in every way.
By changing the handedness of the inside polarizer 17, one can
select a transmissive display utilizing colors derived from either
primary color sub-pixels or complementary color sub-pixels. As
illustrated above, the sub-pixels yield the primary colors. By
changing the handedness of the inside polarizer 17 to produce
RHCPL, the complementary colors, such as the cyan (aqua), magenta
(purple) and yellow, are produced in the transmissive mode. When
this is done, the reflective characteristics remain unchanged, but
the primary colors, although desaturated, have a four fold increase
in their luminous flux, while still maintaining a black field
capability. This brightness increase is illustrated by the
distribution of FIG. 17. The purity of these colors is reduced due
to the fact that half of the light flux is in the skirts of the
spectral distributions. The colors and switching logic are shown in
Table II. As noted the embodiment of FIG. 13A best performs in the
reflective mode and in the event that only the reflective mode were
to be used, one could improve the color contrast slightly by
replacing the inside polarizer 17 and the light source 11 with a
light absorber 27 as is illustrated in FIG. 13B. This modification
could also be made to other embodiments of the invention.
The final embodiment of the invention is not a transflective
device, but it is closely related to the aforementioned techniques.
This is a high brightness transmissive device, well suited for
projection displays. It is potentially a very low cost device. The
embodiment is illustrated in FIG. 18 & 19, and the display's
characteristics are presented in Table III. The performance
characteristics for the device in the transmissive mode are the
same as those of the embodiment of FIG. 13A in the reflective mode.
But unlike other embodiments, the color elements 26 are on the
output side of the LCD. Note, that in the embodiment of FIG. 19,
these color elements may even be placed upon the outside of the
LCD, provided a thin faceplate is used and the light source is
reasonably well collimated. Another possibility in this embodiment
is the use of a CLC inside polarizer, where the inside polarizer
consists of merely a three layer filter/mirror of RHCPL reflecting
material. This filter then allows a simple, low cost, high
efficiency light system by merely having some of the light (RHCPL)
reflected from the polarizing filter returned to the filter after
being reflected from a mirror, wherein its handedness is changed to
LHCPL. This embodiment constitutes a very low cost color display,
providing nearly the same brightness and cost as a black and white
display. The color capability can be increased at the expense of
the display resolution. For the present three cell triad, with
three levels of filter/mirrors there are eight switching states,
but if the number of sub-pixels in the color pixel is increased
together with the number of filter/mirrors within each sub-pixel,
then more color/switching states are possible. The number of
switching states is two to the power of the number of sub-pixels in
the pixel, so that a six sub-pixel display will yield 64 switched
states and as many different color states. The great limitation for
these "always on", high brightness embodiments, is their inability
to do halftones or color modulation. This is because a sub-pixel is
never "off" and the color can only be switched between
complementary colors. Thus modulating the polarization of a
switching cell 4, desaturates the color of a sub-pixel, with all
sub-pixels desaturating to white.
The operation of this cell is very similar to that of other
embodiments. The pixel format can be the same and is shown in FIG.
13A, wherein the operation of the embodiment is as follows: In
FIGS. 18 and 19, the light 10 from the light source 11 passes
through the inside polarizer 17, becoming LHCPL 17a. The light 17a
traverses the backplate 6 and rear electrodes 5, entering the LCD
switching cell 4, where it 17a is either unaffected by the cell 4
("on" state) or it has its 17a handedness changed to RHCPL ("off"
state). One state transmits a primary color to the viewer 9 or the
projection lens 27 and screen 28, while the other state transmits
the complementary color. Each sub-pixel displays a different
primary and complementary color set. For the triad format of FIG.
14, this yields the color/switching as described in Table III.
If a less bright, more conventional color display with half-tone
capability, comprised of the three primary colors and all
combinations of two or more of the primary colors, on a black
field, is desired, then the composition of the color elements 26
within the pixels can be changed, as illustrated in FIGS. 20. In
these instances, a higher brightness display can be composed of
pixels, the sub-pixel elements of which, display complementary
colors, when disposed as illustrated in FIG. 20A or primary colors,
when disposed as illustrated in FIG. 20B. The complementary color
display has high brightness, less saturated spectral distributions
as illustrated in FIGS. 15, 16 and 17. In the illustrations of
FIGS. 20, LH CLC filter/mirror layers can be replaced by a RH
circular polarizing filter 12, as illustrated in FIG. 21. This then
allows the deposition of just one or two CLC filter/mirror layers
within the polarization modulating cell 4 or on the outside, as
illustrated in FIGS. 18 and 19. In these embodiments, the light 10
from the light source 11 is polarized by the inside polarizer 17,
becoming LHCPL 17a. The light 17a transits the backplate 6 and the
inside electrodes 5 and passes through the cell 4, where its
polarization orientation is either changed or left unaltered. When
the light 17a is unaltered it passes through the color elements 26
and is absorbed by the outside polarizer 12. When the light 17a has
its handedness changed by the modulation cell 4, one or two colors
of the light 17a is reflected by the color elements 26. The number
of colors produced by a sub-pixel is dependent upon the number of
filter/mirror layers removing light from the illumination source,
as illustrated in FIGS. 20a and 20b. The remaining two or one
colors of light 17a respectively, pass through the outside
polarizer 12 to the viewer 9. The light reflected by the color
elements 26 traverses the cell 4, passes through the electrodes 5,
the backplate 6 the inside polarizer 17 and is absorbed in the
light source 11.
TABLE I
__________________________________________________________________________
STATES A B C D E F on off on off on off on off on off on off G H
CELL 1 2 & 3 2 & 3 1 2 1 & 3 1 & 3 2 3 1 & 2 1
& 2 3 all - on all - off
__________________________________________________________________________
REFL 1 RED GREEN GREEN RED GREEN RED RED GREEN & BLUE &
BLUE & BLUE & BLUE 2 RED & GREEN GREEN RED & RED
& GREEN GREEN RED & BLUE BLUE BLUE BLUE 3 RED & BLUE
RED & BLUE BLUE RED & BLUE RED & GREEN GREEN GREEN
GREEN net RED AQUA GREEN PURPLE BLUE YELLOW WHITE 2X WHITE color
TRANS. 1 BLACK RED RED BLACK RED BLACK BLACK RED 2 GREEN BLACK
BLACK GREEN GREEN BLACK BLACK GREEN 3 BLUE BLACK BLUE BLACK BLACK
BLUE BLACK BLUE net AQUA RED PURPLE GREEN YELLOW BLUE BLACK WHITE
color
__________________________________________________________________________
TABLE II
__________________________________________________________________________
STATES A B C D E F on off on off on off on off on off on off G H
CELL 1 2 & 3 2 & 3 1 2 1 & 3 1 & 3 2 3 1 & 2 1
& 2 3 all - on all - off
__________________________________________________________________________
REFL 1 RED GREEN GREEN RED GREEN RED RED GREEN & BLUE &
BLUE & BLUE & BLUE 2 RED & GREEN GREEN RED & RED
& GREEN GREEN RED & BLUE BLUE BLUE BLUE 3 RED & BLUE
RED & BLUE BLUE RED & BLUE RED & GREEN GREEN GREEN
GREEN net RED AQUA GREEN PURPLE BLUE YELLOW WHITE 2X WHITE color
TRANS. 1 GREEN & BLACK BLACK GREEN & BLACK GREEN &
GREEN & BLACK BLUE BLUE BLUE BLUE 2 BLACK RED & RED &
BLACK BLACK RED & RED & BLACK BLUE BLUE BLUE BLUE 3 BLACK
RED & BLACK RED & RED & BLACK RED & BLACK GREEN
GREEN GREEN GREEN net AQUA RED PURPLE GREEN YELLOW BLUE 2X WHITE
BLACK color
__________________________________________________________________________
TABLE II
__________________________________________________________________________
STATES A B C D E F on off on off on off on off on off on off G H
CELL 1 2 & 3 2 & 3 1 2 1 & 3 1 & 3 2 3 1 & 2 1
& 2 3 all - on all - off
__________________________________________________________________________
TRANS. 1 GREEN & RED RED GREEN & RED GREEN & GREEN
& RED BLUE BLUE BLUE BLUE 2 GREEN RED & RED & GREEN
GREEN RED & RED & GREEN BLUE BLUE BLUE BLUE 3 BLUE RED
& BLUE RED & RED & BLUE RED & BLUE GREEN GREEN
GREEN GREEN net AQUA RED PURPLE GREEN YELLOW BLUE 2X WHITE WHITE
color
__________________________________________________________________________
* * * * *